U.S. patent application number 12/468453 was filed with the patent office on 2010-11-25 for coaxial attenuator and method of manufacture.
Invention is credited to Hatem Aead, Mark Alan Imbimbo, Ronald Joseph Vecchio.
Application Number | 20100295637 12/468453 |
Document ID | / |
Family ID | 43124204 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100295637 |
Kind Code |
A1 |
Aead; Hatem ; et
al. |
November 25, 2010 |
Coaxial Attenuator and Method of Manufacture
Abstract
A coaxial attenuator is provided. The attenuator includes a
central body with first and second sockets at opposite ends
thereof, outer conductors threadably engageable with the first and
second sockets, inner conductors coaxial with the outer conductors,
a resistive element or "chip" positioned within the central body,
and a floating shroud or jack adapter captured between the central
body and one of the outer conductors. Transverse slots are formed
in ends of the inner conductors to create flexible ends which
contact and bias sides of the resistive element. The floating
shroud includes an internal, annular projection which is captured
between a shoulder formed in the outer conductor and a side of the
central body, allowing the shroud to be captured on the attenuator
while permitting movement of the shroud with respect to the central
body and the outer conductor.
Inventors: |
Aead; Hatem; (West Paterson,
NJ) ; Vecchio; Ronald Joseph; (Morris Plans, NJ)
; Imbimbo; Mark Alan; (Butler, NJ) |
Correspondence
Address: |
MCCARTER & ENGLISH, LLP NEWARK
FOUR GATEWAY CENTER, 100 MULBERRY STREET
NEWARK
NJ
07102
US
|
Family ID: |
43124204 |
Appl. No.: |
12/468453 |
Filed: |
May 19, 2009 |
Current U.S.
Class: |
333/81A ;
29/592.1 |
Current CPC
Class: |
Y10T 29/49002 20150115;
H01P 1/225 20130101 |
Class at
Publication: |
333/81.A ;
29/592.1 |
International
Class: |
H01P 1/22 20060101
H01P001/22; H01P 11/00 20060101 H01P011/00 |
Claims
1. A coaxial attenuator, comprising: a central body having first
and second sockets on opposite ends thereof; first and second outer
conductors engageable with the first and second sockets; first and
second inner conductors coaxial with the first and second outer
conductors; first and second flexible ends formed in the first and
second inner conductors; and a resistive element positioned within
the central body and biased by the first and second flexible ends
of the first and second inner conductors.
2. The attenuator of claim 1, wherein the first and second flexible
ends are formed by one or more transverse slots formed in the first
and second conductors.
3. The attenuator of claim 2, wherein the first and second flexible
ends contact sides of the resistive element and provide electrical
connections between the resistive element and the first and second
inner conductors.
4. The attenuator of claim 1, further comprising first and second
dielectric portions between the first and second inner conductors
and the first and second outer conductors.
5. The attenuator of claim 4, further comprising first and second
epoxy materials for interconnecting the first and second outer
conductors, the first and second inner conductors, and the first
and second dielectric portions.
6. The attenuator of claim 5, wherein the first and second epoxy
materials are injected into apertures formed in the first and
second outer conductors and the first and second dielectric
portions.
7. The attenuator of claim 6, wherein the first and second inner
conductors include recessed portions for contacting the first and
second epoxy materials.
8. The attenuator of claim 1, further comprising a floating shroud
captured between the first outer conductor and the first
socket.
9. The attenuator of claim 8, wherein the floating shroud includes
an annular projection between a shoulder of the first outer
conductor and a side of the first socket when the first outer
conductor is threaded into the first socket.
10. The attenuator of claim 9, wherein a portion of the first outer
conductor extends through the floating shroud.
11. The attenuator of claim 1, wherein the central body includes a
nest for receiving the resistive element.
12. The attenuator of claim 1, wherein the first and second outer
conductors are threadably engageable with the first and second
sockets.
13. The attenuator of claim 1, further comprising solder
connections for electrically connecting the resistive element to
the first and second outer conductors of the attenuator.
14. A method for manufacturing a coaxial attenuator, comprising the
steps of: forming an central body having first and second sockets
at ends thereof, first and second outer conductors, and a shroud;
forming first and second inner conductors with flexible ends;
inserting the first and second inner conductors into first and
second dielectric portions; inserting the first and second
dielectric portions and the first and second inner conductors into
the first and second outer conductors; injecting an epoxy material
into the first and second outer conductors and the first and second
dielectric portions; allowing the epoxy material to cure so that
the first and second outer conductors, the first and second
dielectric portions, and the first and second inner conductors are
bonded together; inserting a resistive element into the central
body; inserting an end of the first outer conductor through an
aperture in the shroud; and threadably engaging ends of the first
and second outer conductors into the first and second sockets of
the central body so that the flexible ends of the first and second
inner conductors contact and bias sides of the resistive element to
maintain contact with the resistive element.
15. The method of claim 14, further comprising forming the flexible
ends in the first and second inner conductors by cutting transverse
slots in ends of the first and second inner conductors.
16. The method of claim 14, further comprising forming recessed
portions in the first and second inner conductors prior to
inserting the first and second inner conductors into the first and
second dielectric portions.
17. The method of claim 14, further comprising drilling
longitudinal and transverse apertures in the first and second
dielectric portions prior to inserting the first and second inner
conductors into the first and second dielectric portions.
18. The method of claim 17, further comprising drilling transverse
apertures in the first and second outer conductors prior to
inserting the first and second inner conductors and the first and
second dielectric portions into the first and second outer
conductors.
19. The method of claim 18, further comprising aligning the
transverse apertures of the first and second outer conductors and
the first and second dielectric portions prior to injecting the
epoxy material.
20. The method of claim 19, wherein the step of injecting the epoxy
material comprises injecting the epoxy material into the apertures
of the first and second outer conductors and the first and second
dielectric portions.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a coaxial attenuator.
[0003] 2. Related Art
[0004] An attenuator is a resistive electrical device which reduces
the power (usually expressed in decibels or "dB") of an electrical
signal. Often, attenuators are used with radio-frequency (RF)
equipment to reduce the power level of RF signals to a desired
level. Attenuators operate at specific frequencies, and can be
fixed (i.e., the attenuator provides fixed attenuation levels
across a desired frequency range) or variable (i.e., the attenuator
can be adjusted to provide varying attenuation levels across a
desired frequency range).
[0005] Frequently, attenuators are coaxial in design, such that an
inner conductor of the attenuator is positioned within (i.e.,
coaxial with) an outer conductor, and is insulated therefrom by a
dielectric. Coaxial connectors are provided so that the attenuator
can be connected "inline" between two devices (e.g., between an
antenna and a receiver), or between coaxial cables connected to
such devices. Additionally, a resistive element or "chip" is
positioned within the attenuator body, and is connected between the
outer (or, ground) conductor and the inner conductor, thereby
providing an electrical resistance between the conductors which
reduces the power level of an electrical signal passed through the
attenuator.
[0006] It is known to use springs and associated components to
contact and bias the sides of a chip in an attenuator, so that the
chip is held in a fixed position within the attenuator. Such an
arrangement also completes an electrical connection between the
chip and the inner conductor of the attenuator. Unfortunately, such
springs/components are difficult to assemble, are easily lost due
to their small size, and additional materials and manufacturing
processes are required for fabrication.
[0007] It is also known to provide a threaded "shroud" or jack
adapter on one end of the attenuator, which can be rotated with
respect to the attenuator body and threadably engaged with a
complementary coaxial connector (e.g., a connector on a piece of RF
equipment, or a connector of a coaxial cable). In one such design,
a C-shaped clip is fit into a recess and used to capture the shroud
on the attenuator. However, such a design is difficult to assemble,
and is relatively expensive because it requires additional
manufacturing steps and materials to produce.
SUMMARY OF THE INVENTION
[0008] The present invention relates to a coaxial attenuator having
a central body with first and second sockets at opposite ends
thereof, outer conductors threadably engageable with the first and
second sockets, inner conductors coaxial with the outer conductors,
a resistive element or "chip" positioned within the central body,
and a floating shroud or jack adapter captured between the central
body and one of the outer conductors. One or more transverse slots
are formed in ends of the inner conductors to create flexible ends
which contact the resistive element, and which are compressed
against sides of the resistive element when the outer conductors
are threaded into the first and second sockets. The floating shroud
includes an internal, annular projection which is captured between
one of the outer conductors of the attenuator and the central body.
One end of the outer conductor can be inserted through the shroud
and can be threadably mated with one of the sockets of the central
body, so that the annular projection is captured between a shoulder
formed in the outer conductor and a side of the central body. This
allows the shroud to be captured on the attenuator while permitting
movement of the shoud (e.g., rotation, angulation, and translation)
with respect to the central body and the outer conductor.
[0009] The present invention also relates to a method for
manufacturing a coaxial attenuator. A central body having first and
second sockets at ends thereof are formed, as well as first and
second outer conductors and a shroud. First and second inner
conductors with transverse slots forming flexible ends are then
formed. The first and second inner conductors are inserted into
first and second dielectric portions, and the first and second
dielectric portions and the first and second inner conductors are
inserted into the first and second outer conductors. An epoxy
material is injected into the first and second outer conductors and
the first and second dielectric portions, and allowed to cure so
that the first and second outer conductors, the first and second
dielectric portions, and the first and second inner conductors are
bonded together. A resistive element is inserted into a nest formed
in the central body, and the resistive element is soldered to the
central body to create a ground connection between the resistive
element and the outer conductors. One end of the first outer
conductor is inserted through an aperture in the shroud, and the
ends of the first and second outer conductors are threaded into the
first and second sockets of the central body so that the flexible
ends of the first and second inner conductors contact and bias
sides of the resistive element, and so that the shroud is captured
between the first outer conductor and the central body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The foregoing features of the invention will be apparent
from the following Detailed Description of the Invention, taken in
connection with the accompanying drawings, in which:
[0011] FIG. 1 is a partial cross-sectional view showing the coaxial
attenuator of the present invention;
[0012] FIGS. 2-4 are cross-sectional views showing construction of
the coaxial attenuator of FIG. 1 in greater detail;
[0013] FIG. 5 is a perspective view showing construction of the
coaxial attenuator of the present invention in greater detail;
[0014] FIG. 6 is an exploded view of the components shown in FIG.
5;
[0015] FIGS. 7-8 are cross-sectional views of the components shown
in FIG. 5, taken along the lines 7-7 and 8-8 of FIG. 5,
respectively; and
[0016] FIGS. 9-10 are graphs showing return loss and attenuation
characteristics, respectively, of the coaxial attenuator of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention relates to a coaxial attenuator, as
discussed in detail below in connection with FIGS. 1-10.
[0018] FIG. 1 is a cross-sectional view of the coaxial attenuator
of the present invention, indicated generally at The attenuator 10
includes a central body 12, a floating shroud (or, jack adapter) 14
which is threadably attachable to a coaxial connector (e.g., a
coaxial connector on a transceiver, amplifier, antenna, cable,
etc.), and a jack 16 for connection to another piece of equipment
or a cable. The central body 12 includes a housing 18 which houses
and protects a resistive element 28 positioned therein, and first
and second sockets 20, 30 on opposite sides of the housing 18. The
first socket 20 includes internal threads 22 which receive a first
threaded outer conductor 48. A recess 24 is provided in the housing
18 for receiving the outer conductor 48. A central space or "nest"
26 is provided in the housing 18 for receiving the resistive
element 28. The second socket 30 includes internal threads 32 for
receiving a second threaded outer conductor 84 of the jack 16. A
recess 34 is also provided in the housing 18 for receiving the
outer conductor 84. When the outer conductors 48, 84 are threaded
into the respective sockets 20, 30, a complete electrical path is
formed between the outer conductors 48, 84 and the central body 12
(including the housing 18). Such electrical path provides the
"ground" electrical path for the attenuator 10.
[0019] It is noted that the attenuator 10 could be provided with
two jacks, or two shrouds, or any combination thereof, by simply
threading such components into the first and second sockets 20, 30,
as desired. Also, the shapes and configurations of such components
could conform to any suitable, coaxial connector standards, such as
types C, F, N, BNC, TNC, PL-259, SO-239, 7/16 DIN, SMA, 2.44 mm,
etc., without departing from the spirit or scope of the present
invention.
[0020] The shroud 14 includes a "nut" region 40 having two or more
wrench flats (e.g., the nut region 40 could be hexagonal in shape,
as is common with some screw-in coaxial connectors), a rounded,
recessed portion 42 at one end of the shroud 14, and an annular
projection 44 at an opposite end of the shroud 14. The annular
projection 44 is captured within an annular recess 49 which is
formed when one end of the outer conductor 48 is threaded into the
first socket 20, so that the shroud 14 is captured on the
attenuator 10 but moves freely with respect to the attenuator 10
(i.e., the shroud 14 can rotate, pivot, and translate with respect
to the central body 12 and the outer conductor 48). An inner region
46 is provided in the shroud 14 to accept a coaxial connector. The
outer conductor 48, which could be threaded at both ends, provides
a first (ground) electrical connection for the attenuator 10 when
the shroud 14 is threaded onto and tightened against a
complementary coaxial connector of a piece of equipment, or a
cable. Optionally, a disk 50 could be provided at one end of the
outer conductor 48.
[0021] A dielectric portion 54 surrounds an inner conductor 56,
which provides a second electrical connection for the attenuator
when the shroud 14 is threaded onto and tightened against a
complementary coaxial connector of a piece of equipment, or a
cable. The dielectric portion 54 insulates the inner conductor 56
from the outer conductor 48. An epoxy material 52 is injected into
a recess in the dielectric portion 54, and, when cured, bonds the
outer conductor 48, the dielectric portion 54, and the inner
conductor 56 together to form a tight mechanical connection between
these parts. The inner conductor 56 includes a recessed portion 58
at the area of bonding with the epoxy material 52 so as to retain
the inner conductor 56 in a fixed position within the dielectric
portion 54. The opposite end of the inner conductor includes a
flexible end 60 formed by one or more transverse slots in the inner
conductor 56, which provide spring-like flexibility and allow the
inner conductor 56 to be biased against one end of the resistive
element 28 when the outer conductor 48 is threaded into the first
socket 20 of the central body 12.
[0022] The jack 16 includes an outer conductor 84 having a threaded
outer end 70, a socket portion 72, and a recess 74. The jack 16
receives a second coaxial connector (e.g., a connector attached to
an end of a coaxial cable), which can be threadably connected
thereto, such that the outer conductor 84 makes electrical contact
with the outer (ground) conductor of such a connector when the
connector is threaded onto the threaded outer end 70 of the jack
16. The recess 74 receives and makes electrical contact with an
inner conductor of the second coaxial connector/cable, and is
formed in one end of an inner conductor 76 of the connector 16. The
inner conductor 76 extends through an aperture formed in a
dielectric portion 78, which insulates the inner conductor 76 from
the outer conductor 84. An epoxy material 80 is injected into a
recess in the dielectric portion 78, and, when cured, glues the
outer conductor 84, the dielectric portion 78, and the inner
conductor 76 together to form a tight mechanical connection between
these parts. The inner conductor 76 includes a recessed portion 82
at the area of bonding with the epoxy material 80 so as to retain
the inner conductor 76 in a fixed position within the dielectric
portion 78. The opposite end of the inner conductor 76 includes a
flexible end 90 formed by one or more transverse slots in the inner
conductor 76, which provides spring-like flexibility and allows the
inner conductor 76 to be biased against one end of the resistive
element 28 when the outer conductor 84 is threaded into the socket
30 of the central body 12.
[0023] The central body 12, shroud 14, outer conductors 48, 84, and
inner conductors 56, 76 could be formed from any suitable,
electrically-conductive, metallic materials, such as brass, copper,
stainless steel, gold, silver, aluminum, or any other suitable
materials. Additionally, the dielectric portions 54, 78 could be
formed form TEFLON.RTM., plastic, or any other suitable dielectric
material. Also, the epoxy materials 52, 80 could be substituted
with any suitable adhesive material, as well as a rubber material
which frictionally engages components of the attenuator 10 to hold
such components together.
[0024] FIG. 2 is a cross-sectional view showing construction of the
attenuator 10 of FIG. 1 in greater detail. The inner conductor 76
includes a contact end 92 which contacts and is biased against an
edge 36 of the resistive element 28. One or more transverse slots
94 permit the flexible end 90 of the inner conductor 76 to be
compressed, and provide spring-like flexibility. Construction of
the flexible end 60 of the inner conductor 56 shown in FIG. 1 is
identical to the construction of the flexible end 90 of the inner
conductor 76.
[0025] FIG. 3 is a cross-sectional view showing the resistive
element 28 and nest 26 of FIG. 1 in greater detail. As mentioned
above, the resistive element 28 is positioned within the nest 26,
which houses and protects the resistive element 28. Solder
connections 38 are provided between the resistive element 28 and
the housing 18, which is in electrical connection with the outer
conductors 48 and 84. The outer conductors 48 and 84 are at ground
potential, and the solder connections 38 thus provide a path to
ground for the resistive element 28.
[0026] FIG. 4 is a cross-sectional view showing capturing of the
shroud 14 of FIG. 1 in greater detail. When the outer conductor 48
is threaded into the socket 20, an annular recess 49 is created,
such that the annular projection 44 is captured between a shoulder
55 of the outer conductor 48 and a side 21 of the socket 20. This
arrangement permits motion (i.e., rotation, translation, and
angulation) of the shroud 14, and obviates the need for a "C" clip
as is used in conventional attenuators to retain the shrouds
thereof. Accordingly, this reduces component count and results in
simple assembly.
[0027] FIG. 5 is a perspective view showing construction of the
attenuator of the present invention in greater detail. As can be
seen in FIG. 5, the dielectric portions 54, 78 and the nest 26 can
be cylindrical in shape. The epoxy materials 52, 80 extend through
apertures formed in the dielectric portions 54, 78. The resistive
element 28 and inner conductors 56, 76 of FIG. 1 (not shown in FIG.
5) are positioned within the housing 18 and the dielectric portions
54, 78, respectively.
[0028] FIG. 6 is an exploded view of the components shown in FIG.
5. The dielectric portion 54 includes an aperture 100 which
receives the inner conductor 56. Optionally, the dielectric portion
54 could include a stepped portion 96, as shown in FIG. 6. If the
stepped portion 96 is not provided, empty space serves as a
dielectric in place of the stepped portion 96 (i.e., as shown in
FIG. 1). The epoxy material 52 includes an aperture 53 which
receives the recessed portion 58 of the inner conductor 56.
Similarly, the dielectric portion 78 includes an aperture 102 which
receives the inner conductor 76. Optionally, the dielectric portion
78 could include a stepped portion 98, as shown in FIG. 6. If the
stepped portion 98 is not provided, empty space serves as a
dielectric in place of the stepped portion 98 (i.e., as shown in
FIG. 1). The epoxy material 80 includes an aperture 81 which
receives the recessed portion 82 of the inner conductor 76. The
flexible ends 60, 90 contact and are biased against the resistive
element 28, and electrically connect the resistive element 28 to
the inner conductors 56, 76. The nest 26 extends along the length
of the housing 18, and receives the resistive element 28.
[0029] FIGS. 7-8 are cross-sectional views of the components shown
in FIG. 5 and taken along the lines 7-7 and 8-8 of FIG. 5,
respectively. As can be seen in these views, the epoxy materials
52, 80 retain the inner conductors 56, 76 in fixed positions within
the dielectric portions 54, 78. Also, as can be seen in FIGS. 7-8,
the flexible ends 60, 90 of the inner conductors 56, 76 contact and
are biased against the resistive element 28.
[0030] FIGS. 9-10 are graphs showing return loss and attenuation
characteristics, respectively, of the coaxial attenuator of the
present invention. As can be seen in FIG. 9, return losses peak at
approximately -17.5 dB at a frequency of 24 GHz, and are lowest at
frequencies below 2 GHz. As shown in FIG. 10, the attenuation
levels peak at approximately -2.9 dB at an operating frequency of
about 20 GHz, and begin to drop off at about 24 GHz. The coaxial
attenuator of the present invention can effectively operate at
frequency ranges of 2-24 GHz and power levels of less than -40 dB
to greater than -17 dB, but these parameters can be varied by
altering the physical dimensions and/or materials of the coaxial
attenuator, as desired.
[0031] The coaxial attenuator 10 of the present invention can be
manufactured as follows. First, the dielectric portions 54, 78 are
formed, and are drilled to create longitudinal and transverse
apertures for receiving the inner conductors and the epoxy
materials, respectively. Then, the inner conductors 56, 76 are
milled to a desired shape, and the recessed portions 58, 82 are
milled in the inner conductors 56, 76. The flexible ends 60, 90 are
then formed by cutting slots into the inner conductors 56, 76.
Then, the inner conductors 56, 76 are inserted through the
apertures of the dielectric portions 54, 78.
[0032] The outer conductors 48, 84, the central body 12 (including
the housing 18, sockets 20-30, and the nest 26), and the shroud 14
are milled to the shapes disclosed herein using conventional
milling techniques. Transverse apertures are drilled in the outer
conductors 48, 84 for accepting epoxy. Then, the insert assemblies
discussed above (i.e., the inner conductors 56, 76 and the
dielectric portions 54, 78) are inserted into the outer conductors
48, 84 so that the transverse apertures thereof are aligned with
each other. Once aligned, the epoxy materials 52, 80 are injected
into the transverse apertures of the outer conductors 48, 84 and
the dielectric portions 54, 78. The epoxy materials 52, 80 are then
left to cure to form completed outer and inner conductor
assemblies.
[0033] The resistive element 28 is located within the nest 26 of
the housing 18 of the central body 12, and the resistive element 28
is soldered to the housing 18. Then, one end of the outer conductor
48, as well as the dielectric portion 54 and the inner conductor 56
bonded thereto, are inserted through an aperture in the shroud 14,
and the outer conductor 48 is threaded into the sockets in the
central body so that the annular projection 44 of the shroud is
captured between the shoulder 55 of the outer conductor 48 and the
side 21 of the central body 12. Finally, the outer conductor 84 is
threaded into the second socket 30 of the central body 12, forming
a complete coaxial attenuator. When the outer conductors are
tightened into the first and second sockets, the flexible ends 60,
90 of the inner conductors contact the resistive element 28 and
bias same to maintain contact. Of course, it is noted that the
manufacturing steps disclosed herein could be varied as desired
without departing from the spirit or scope of the present
invention.
[0034] Having thus described the invention in detail, it is to be
understood that the foregoing description is not intended to limit
the spirit or scope thereof. What is desired to be protected is set
forth in the following claims.
* * * * *